Marine Science Notes Series Properties of Water Marine Science Notes Series

Water Molecule and Bonding Forces I. London Forces: Intramolecular a) Covalent Bonds: sharing of electrons between Hydrogen and Oxygen b) Van der Waals – forces within the water molecule c) Hydrogen Bonds – keeping a network of water molecules together (~105 0 angle)

Energy & Water Heat Values are measured in calories and joules. a) a calorie is the amount of heat energy needed to raise the temperature of 1 gram of water by 10C This is sometimes called specific heat b) There are energy values when water changes state from a solid to a liquid to a gas (Latent Heat of… Fusion and of Vaporization) c) Temperature is an indirect function of heat energy F= 9/5 C + 32 C = 5/9 (F – 32)

Specific Heat of Salt Water? We will calculate the specific heat of salt water, but will see how accurate we are by determining the specific heat of a known metal Heat Loss or Gain = m (Cp) T Cp = Specific Heat

Special Properties of Water Water can break salts down into ions (which are charged particles) Cations are positive ions Anions are negative ions b) Cohesion – This holds a water molecule together as a “body” c) Adhesion – the ability of water to bond with other molecules d) Viscosity – the ability of a liquid to flow e) Density – varies with temperature*

Seawater The density of seawater at 4 oC is approximately 1.0278 g/cm3 The freezing point of seawater is -1.33 oC Open ocean water has a salinity of 35 g/kg

Eleven Major Constituents Chloride Sulfate Bromide Bicarbonate Fluoride Boron Strontium Calcium Potassium Magnesium Sodium Residence Time of Chloride is 80 million years Residence Time of Sodium is 60 million years

Light and Seawater Visible light ranges from 350 to 720 nm as part of an electromagnetic light visibl emission -In the first 1 meter – 60% of light is absorbed -In the first 11 meters, 80% of light is absorbed -Below 1000 m, no light penetrates Attenuation

Nature Reviews Microbiology 2007

Gases in water Solubility is determined by Temperature Salinity Density It is measured in mg/L or ppm. The understood gases are Oxygen and Carbon dioxide